Moore's law describes a long-term trend in the history of computing hardware. In particular, since the invention of the integrated circuit in 1958, the number of transistors that can inexpensively be included in an integrated circuit has increased exponentially, doubling about every two years. This trend was first reported on by Gordon E. Moore in 1965 and has continued to the present. One view is that this scaling trend will continue for another decade. A second view is that additional functionalities will be required and that simple scaling is near an end, “more than the Moore”. In either case, new materials and new device structures are emerging to meet the challenges posed by the technology and economic considerations.
The capabilities of digital electronic devices, such as processing speed, memory capacity, the number and size of pixels in digital cameras, etc, are strongly linked to Moore's law, with all such capabilities improving at roughly exponential rates as well. This increase in capability has dramatically increased the usefulness of digital electronics in nearly every segment of the world economy.
In order to continue the trend for semiconductor chip integration in accordance with either Moore's law or the “more than the Moore” viewpoint, it will be necessary to use new materials incorporated with silicon-based IC chips. These new materials will need to provide enhanced chip performance as well as help reduce unit cost.
Numerous group 2 and transition (group 3 10 12) metals have been suggested in recent years as candidates for providing critical functionalities in electronic devices. However, precursors for group 2 and transition metals are generally solid materials that are difficult to use in vapor phase deposition processes, such as ALD, CVD and MOCVD processes. In ALD processes, the requirements for precursor materials are far more stringent than the requirements for precursors used in CVD or MOCVD processes. In particular, any precursor decomposition or self-growth without a co-reactant can result in quality issues, such as higher impurity and non-uniformity in the film. Decomposition occurs at elevated temperatures for some standard amine based liquid precursors. Strong inter-molecular and intra-molecular interactions of and for some thermally stable solid precursors could result in polymerization and self-growth often occurs during the thin film growth. Furthermore, some of those solid precursor materials suffer decomposition or solidification when heated in attempts to sublimate measurable vapors for use in deposition of thin specialty films on a semiconductor wafer.
Therefore, there is a need in the art for improvements to precursors for use in vapor phase deposition processes.